Method for operating air conditioner

ABSTRACT

Disclosed herein is a method for operating an air conditioner which is capable of achieving the effective operation of a plurality of indoor units. The method comprises the steps of: a) receiving operating state information of the indoor units connected to one outdoor unit; b) determining whether or not the amount of refrigerant to be distributed into the indoor units needs to be regulated, based on the operating state information of the indoor units; and c) regulating the amount of the refrigerant to be distributed into the indoor units.

This application claims the benefit of the Korean Patent Application No.10-2004-105329, filed on Dec. 14, 2004 which is hereby incorporated byreference as if fully set forth herein.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a method for operating an airconditioner, and more particularly, to a method for operating an airconditioner which is capable of achieving the effective operation of aplurality of indoor units.

2. Discussion of the Related Art

Recently, an air conditioner of a type wherein a plurality of indoorunits are connected to one outdoor unit has been used in high buildingsor other buildings having a plurality of rooms. This type of airconditioner is conventionally referred to as a multi-unit airconditioner. The multi-unit air conditioner uses a plurality of indoorunits, which are mounted in a plurality of rooms, respectively, to serveas coolers or heaters, while using one outdoor unit in common.

The outdoor unit includes a compressor to compress a refrigerant to ahigh-pressure state, a 4-way valve to switch the flow path of therefrigerant, discharged from the compressor, in accordance with theoperation mode, that is, cooling mode or heating mode, of each of theindoor units, and an outdoor heat exchanger to perform heat exchangebetween the refrigerant, introduced into the outdoor heat exchanger, andoutdoor air.

Additionally, a plurality of expansion valves for expanding therefrigerant heat-exchanged in the outdoor heat exchanger are provided onconduits connected to the indoor units, respectively. Here, the numberof the expansion valves is identical to that of the indoor units.

Each of the indoor units for cooling or heating the associated roomincludes an indoor heat exchanger to perform heat exchange betweenindoor air and the refrigerant, and an indoor fan to forcibly circulatethe indoor air into the indoor heat exchanger, in order to improve theheat-exchange efficiency of the indoor heat exchanger. While passingthrough the indoor heat exchanger, the refrigerant, circulating throughthe indoor units and the outdoor unit, is heat exchanged with the indoorair.

To operate the air conditioner as stated above, the indoor units areprovided with indoor unit controllers, respectively, and the outdoorunit is provided with an outdoor unit controller that communicates withthe respective indoor unit controllers.

When an operation key of an operating panel installed in each of theindoor units is pressed, the corresponding indoor unit controllerreceives an operation signal, and performs a control operation for anindoor fan driver, a blowing direction regulator, an indoor temperaturesensor, an indoor conduit temperature sensor, and the like required inthe indoor unit in accordance with the operation signal. The indoor unitcontroller also outputs a control signal to the outdoor unit controller,so as to enable the outdoor unit controller to perform a controloperation for the compressor, the 4-way valve, and the expansion valvein accordance with the control signal.

In the conventional air conditioner having the above-describedconfiguration, each of the indoor units and the outdoor unit sends andreceives operating information in a one to one ratio. In this case,however, there may be a problem in that the operating state of theindoor units is not considered with regard to the whole indoor unitswhen the operation of the air conditioner is controlled. As a result,the indoor units exhibit uneven operating performance.

That is, when different models of indoor units having the same capacityas each other are used, their indoor heat exchangers may exhibitdifferent capabilities from each other. Also, even if the indoor unitsare of the same model, the indoor units may have a deviation inoperating performance in accordance with various installation conditionsthereof (for example, the lengths, installation heights, branchedshapes, or curvatures of conduits connected to the outdoor unit).

As a result, the indoor units of the conventional air conditioner failto perform an effective operation.

SUMMARY OF THE INVENTION

Accordingly, the present invention is directed to a method for operatingan air conditioner that substantially obviates one or more problems dueto limitations and disadvantages of the related art.

An object of the present invention is to provide a method for operatingan air conditioner which is capable of achieving the effective operationof a plurality of indoor units.

Additional advantages, objects, and features of the invention will beset forth in part in the description which follows and in part willbecome apparent to those having ordinary skill in the art uponexamination of the following or may be learned from practice of theinvention. The objectives and other advantages of the invention may berealized and attained by the structure particularly pointed out in thewritten description and claims hereof as well as the appended drawings.

To achieve these objects and other advantages and in accordance with thepurpose of the invention, as embodied and broadly described herein, amethod for operating an air conditioner comprises the steps of: a)receiving operating state information of a plurality of indoor unitsconnected to one outdoor unit; b) determining whether or not the amountof refrigerant to be distributed into the indoor units needs to beregulated, based on the operating state information of the indoor units;and c) regulating the amount of the refrigerant to be distributed intothe indoor units.

Here, the operating state information may include at least one of thetemperature of air discharged from each of the indoor units, thetemperature of each of indoor unit conduits, the temperature of airsuctioned into each of the indoor units, and a flow rate value of eachof the indoor units.

Preferably, the method may further comprise the step of: confirming thata controller receives the operating state information from all theindoor units.

The step b) may comprise the sub steps of: b1) calculating the operatingperformance of each of the indoor units based on the operating stateinformation; and b2) determining whether or not the amount of therefrigerant to be distributed needs to be regulated, in accordance withthe operating performance of each of the indoor units.

The operating performance may be calculated by the proportion of anactual operating capability in relation to a rated operating capabilityunder a preset operation condition.

The rated operating capability may be a preset temperature of each ofthe indoor units, and the actual operating capability may be thetemperature of air discharged from each of the indoor units under thepreset operation condition.

Preferably, the amount of the refrigerant to be distributed may beregulated when it is determined that there are at least one indoor unithaving the operating performance below 1 and at least one indoor unithaving the operating performance more than 1.

The amount of the refrigerant to be distributed may be regulated in thestep c), so that an increased amount of the refrigerant is introducedinto one or ones of the indoor units having the operating performancebelow 1.

The step b1) may comprise the step of: comparing the temperature of airdischarged from each of the indoor units with the average temperature ofair discharged from all the indoor units, to calculate the operatingperformance.

Preferably, the amount of the refrigerant to be distributed may beregulated when it is determined that there are at least one indoor unitin which the temperature of air discharged therefrom is higher than theaverage temperature and at least one indoor unit in which thetemperature of air discharged therefrom is lower than the averagetemperature.

Preferably, when the indoor units operate in heating mode, the amount ofthe refrigerant to be distributed may be regulated in the step c), sothat an increased amount of the refrigerant is introduced into one orones of the indoor units in which the temperature of air dischargedtherefrom is lower than the average temperature of air discharged fromall the indoor units.

When the indoor units operate in cooling mode, the amount of therefrigerant to be distributed may be regulated in the step c), so thatan increased amount of the refrigerant is introduced into one or ones ofthe indoor units in which the temperature of air discharged therefrom ishigher than the average temperature of air discharged from all theindoor units.

The step b1) may comprise the step of: comparing the temperature of eachof indoor unit conduits with the average temperature of all the indoorunit conduits, to calculate the operating performance.

The amount of the refrigerant to be distributed may be regulated when itis determined that there are at least one indoor unit in which thetemperature of the associated conduit is higher than the averagetemperature and at least one indoor unit in which the temperature of theassociated conduit is lower than the average temperature.

When the indoor units operate in heating mode, the amount of therefrigerant to be distributed may be regulated in the step c), so thatan increased amount of the refrigerant is introduced into one or ones ofthe indoor units in which the temperature of the associated conduit islower than the average temperature of all the indoor unit conduits.

When the indoor units operate in cooling mode, the amount of therefrigerant to be distributed may be regulated in the step c), so thatan increased amount of the refrigerant is introduced into one or ones ofthe indoor units in which the temperature of the associated conduit ishigher than the average temperature.

It is to be understood that both the foregoing general description andthe following detailed description of the present invention areexemplary and explanatory and are intended to provide furtherexplanation of the invention as claimed.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings, which are included to provide a furtherunderstanding of the invention and are incorporated in and constitute apart of this application, illustrate embodiment(s) of the invention andtogether with the description serve to explain the principle of theinvention. In the drawings:

FIG. 1 is a configuration diagram schematically showing an example of anair conditioner which is operable in accordance with an air conditioneroperating method of the present invention;

FIG. 2 is a flow chart illustrating a method for operating an airconditioner in accordance with a first embodiment of the presentinvention;

FIGS. 3A and 3B are flow charts illustrating a method for operating anair conditioner in accordance with a second embodiment of the presentinvention; and

FIGS. 4A and 4B are flow charts illustrating a method for operating anair conditioner in accordance with a third embodiment of the presentinvention.

DETAILED DESCRIPTION OF THE INVENTION

Reference will now be made in detail to the preferred embodiments of thepresent invention, examples of which are illustrated in the accompanyingdrawings. Wherever possible, the same reference numbers will be usedthroughout the drawings to refer to the same or like parts.

First, an example of an air conditioner, which is operable in accordancewith an air conditioner operating method of the present invention, willbe explained in brief with reference to FIG. 1.

As shown in FIG. 1, the air conditioner is a multi-unit air conditioner,and includes a plurality of indoor units 10, 20, and 30, and one outdoorunit 40.

For the sake of the convenience of explanation, the followingdescription defines three indoor units. However, it should be understoodthat the number of the indoor units is not essentially limited thereto.

The outdoor unit 40 includes a compressor 41 to compress a refrigerantto a high-temperature and high-pressure state, a 4-way valve 42 toswitch the flow path of the refrigerant, discharged from the compressor41, in accordance with operation mode (for example, cooling mode orheating mode), and an outdoor heat exchanger 43 to perform heat exchangebetween the circulating refrigerant and outdoor air.

An outdoor fan 44 is arranged at one side of the outdoor heat exchanger43. The outdoor fan 44 sucks outdoor air, and forcibly blows the suckedair toward the outdoor heat exchanger 43, in order to enable the outdoorair heat exchanger 43 to perform effective heat exchange.

A main electronic expansion valve 45 is provided at a main conduitconnected to the outdoor heat exchanger 43. The main electronicexpansion valve 45 controls the temperature of the refrigerantdischarged from the outdoor heat exchanger 43 to regulate theover-heating degree or over-cooling degree of the refrigerant inaccordance with the operation mode of the indoor units.

A plurality of sub electronic expansion valves 11, 21, and 31 areprovided at branched-conduits, which are branched from the main conduitto be connected to the indoor units 10, 20, and 30, respectively.

Each of the sub electronic expansion valves 11, 21, and 31 is operatedunder control of a controller (not shown), in order to enable theassociated indoor unit 10, 20 or 30 to selectively perform an airconditioning operation for the associated room in accordance with theoperation condition of the associated indoor unit 10, 20 or 30. That is,each of the sub electronic expansion valves 11, 21, and 31 regulates theamount of the refrigerant to be distributed into the associated indoorunit 10, 20, or 30, and selectively cuts off the refrigerant supplied tothe associated indoor unit 10, 20, or 30. In particular, the subelectronic expansion valves 11, 21, and 31 expand the circulatingrefrigerant to an easily evaporable low-temperature and low-pressurestate.

The indoor units 10, 20, and 30 include respective indoor heatexchangers 12, 22, and 32 for heating or cooling indoor air, andrespective indoor fans 13, 23, and 33 for forcibly circulating theindoor air into the indoor heat exchangers 12, 22, and 32 to enable theindoor heat exchangers 12, 22, and 32 to effectively perform heatexchange.

When the indoor units 10, 20, and 30 operate in cooling mode in the airconditioner having the above-described configuration, the 4-way valve 42is in an Off state. Accordingly, the refrigerant flows along the path asindicated by solid-line arrows in FIG. 1.

Conversely, when the indoor units 10, 20, and 30 operate in heatingmode, the 4-way valve 42 is in an ON state. In this case, accordingly,the refrigerant flows along the path as indicated by dotted-line arrowsin FIG. 1.

Meanwhile, in the air conditioner as stated above, indoor unitcontrollers (not shown) are mounted in the indoor units 10, 20, and 30,respectively, to receive operating state information of all the indoorunits 10, 20, and 30 and to output the information to an outdoor unitcontroller (not shown) mounted in the outdoor unit 40. The outdoor unitcontroller receives and generalizes the operating state informationoutputted from the indoor unit controllers, to perform a controloperation for the air conditioner.

Now, a method for operating the air conditioner in accordance withseveral embodiments of the present invention will be explained withreference to FIGS. 2, 3A and 3B, and 4A and 4B.

First, a method for operating the air conditioner in accordance with afirst embodiment of the present invention will be explained withreference to FIG. 2.

The method for operating the air conditioner comprises the steps of:(S10) receiving operating state information of the indoor units 10, 20,and 30 connected to the outdoor unit 40; (S20) determining whether ornot the amount of the refrigerant to be distributed into the indoorunits 10, 20, and 30 needs to be regulated, based on the operating stateinformation of the indoor units 10, 20, and 30; and (S30) regulating theamount of the refrigerant to be distributed into the indoor units 10,20, and 30.

Preferably, the operating state information, to be received in the stepS10, may include at least one of the temperature T_(d) of air dischargedfrom each of the indoor units 10, 20, and 30, the temperature T_(p) ofeach of indoor unit conduits, the temperature T_(s) of air suctionedinto each of the indoor units 10, 20, and 30, and the flow rate value ofair of each of the indoor units 10, 20, and 30.

More specifically, each of the indoor unit controllers receives theabove-described operating state information of the associated indoorunit 10, 20, or 30. The indoor unit also outputs the operating stateinformation to the outdoor unit controller. The outdoor unit controllerreceives the operating state information of all the indoor unitcontrollers outputted from the indoor unit controllers, to generalizethe information.

In addition to the above-described procedure, preferably, the method foroperating the air conditioner in accordance with the present inventionfurther comprises the step of: (S11) confirming that the outdoor unitcontroller receives the operating state information from all the indoorunits.

It is important for the safety of operation to confirm that theoperating state information of all the indoor units 10, 20, and 30connected to the outdoor unit 40 is wholly transmitted to the outdoorunit controller.

This has the purpose of preventing the generation of errors when theoperation of the air conditioner is controlled.

Preferably, the determination step S20 comprises the sub steps of: (S21)calculating the operating performances of the indoor units based on theoperating state information; and (S22) determining whether or not theamount of the refrigerant to be distributed needs to be regulated inaccordance with the operating performances of the indoor units.

The operating performance may be calculated by the proportion of anactual operating capability of each of the indoor units in relation to arated operating capability of the corresponding indoor unit under apreset operation condition.

For example, when a preset temperature of each of the indoor units,inputted by a user, is given as the rated operating capability, and thetemperature T_(d) of air discharged from each of the indoor units underthe preset operation condition is given as the actual operatingcapability, the operating performance of each of the indoor units can becalculated.

More specifically, the operating performance can be calculated bydividing the actual temperature T_(d) of air discharged from each of theindoor units by the preset temperature of the corresponding indoor unitunder the preset operation condition.

Of course, the operating performance may be calculated in the samemanner by the use of the temperature T_(s) of air to be suctioned, orthe temperature T_(p) of the associated indoor unit conduit.

Here, the temperature T_(s) of air to be suctioned corresponds to thetemperature of indoor air of each of rooms to be suctioned into theassociated indoor unit. Thus, when the temperature T_(s) of air to besuctioned is given as the actual operating capability, and a presettemperature of each of the rooms, inputted by the user, is given as therated operating capability under a preset operation condition, theoperating performance can be calculated by dividing the temperatureT_(s) of air to be suctioned by the preset temperature of the associatedroom.

Based on the above description, it can be understood that the operatingperformance can be calculated in consideration of the whole operatingstate information as stated above.

The operating performance of each of the indoor units calculated in theabove-described various manners is classified into one having a valuemore than 1 and the other one having a value below 1.

When a certain indoor unit has the operating performance below 1, it ispreferable that the amount of the refrigerant to be distributed beregulated to increase the inflow of refrigerant into the indoor unit.

Conversely, when a certain indoor unit has the operating performancemore than 1, it is preferable that the amount of the refrigerant to bedistributed be regulated to decrease the inflow of refrigerant into theindoor unit.

More preferably, when it is determined that there are at least oneindoor unit having the operating performance below 1 and at least oneindoor unit having the operating performance more than 1, the outdoorunit controller outputs a command to regulate the amount of therefrigerant to be distributed.

The regulation step S30 for regulating the amount of the refrigerant tobe distributed can be carried out by regulating the sub electronicexpansion valves 11, 21, and 31 provided at the respective branchedconduits connected to the indoor units, respectively.

Now, a method for operating the air conditioner in accordance with asecond embodiment of the present invention will be explained withreference to FIGS. 3A and 3B.

FIG. 3A illustrates a method for operating the air conditioner when theindoor units 10, 20, and 30 operate in cooling mode, and FIG. 3Billustrates a method for operating the air conditioner when the indoorunits 10, 20, and 30 operate in heating mode.

The method for operating the air conditioner in accordance with thepresent embodiment comprises the steps of: (S100) receiving operatingstate information of the indoor units 10, 20, and 30 connected to theoutdoor unit 40; (S200) determining whether or not the amount ofrefrigerant to be distributed into the indoor units 10, 20, and 30 needsto be regulated, based on the operating state information of the indoorunits 10, 20, and 30; and (S300) regulating the amount of therefrigerant to be distributed into the indoor units 10, 20, and 30.

Differently from the method for operating the air conditioner inaccordance with the first embodiment of the present invention, theoperating state information of the indoor units 10, 20, and 30, to bereceived in the step S100, includes the temperature T_(d) of airdischarged from each of the indoor units. Hereinafter, only a differencebetween the present embodiment and the above-described first embodimentwill be described for avoiding the overlapping of description.

In the present embodiment, the determination step S200 comprises the substeps of: (S210) comparing the temperature T_(d) of air discharged fromeach of the indoor units with the average temperature T_(da) of airdischarged from the indoor units to calculate the operating performancesof the indoor units; and (S220) determining whether or not the amount ofthe refrigerant to be distributed needs to be regulated in accordancewith the operating performances of the indoor units.

Specifically, the outdoor unit controller collects the temperaturesT_(d) of air discharged from all the indoor units 10, 20, and 30 tothereby calculate the average temperature T_(da). Subsequently, theoutdoor unit controller compares the average temperature T_(da) with thetemperature T_(d) of air discharged from each of the indoor units,thereby calculating the operating performance of each of the indoorunits.

The outdoor unit controller classifies the indoor units into some indoorunits in which the temperature T_(d) of air discharged therefrom ishigher than the average temperature T_(da) and the remainder in whichthe temperature T_(d) of air discharged therefrom is lower than theaverage temperature T_(da).

When the indoor units of the air conditioner operate in cooling mode asshown in FIG. 3A, the amount of the refrigerant to be distributed isregulated in the regulation step S300, so that an increased amount ofthe refrigerant is introduced into one or ones of the indoor units inwhich the temperature T_(d) of air discharged therefrom is higher thanthe average temperature T_(da).

Conversely, when the indoor units of the air conditioner operate inheating mode as shown in FIG. 3B, the amount of the refrigerant to bedistributed is regulated in the regulation step S300, so that anincreased amount of the refrigerant is introduced into one or ones ofthe indoor units in which the temperature T_(d) of air dischargedtherefrom is lower than the average temperature T_(da).

More preferably, when it is determined that there are at least oneindoor unit in which the temperature T_(d) of air discharged therefromis higher than the average temperature T_(da) and at least one indoorunit in which the temperature T_(d) of air discharged therefrom is lowerthan the average temperature T_(da), the outdoor unit controller outputsa command to regulate the amount of the refrigerant to be distributed.

The regulation step S300 for regulating the amount of the refrigerant tobe distributed can be carried out by regulating the sub electronicexpansion valves 11, 21, and 31 provided at the respective branchedconduits connected to the indoor units, respectively.

Now, a method for operating the air conditioner in accordance with athird embodiment of the present invention will be explained withreference to FIGS. 4A and 4B.

FIG. 4A illustrates a method for operating the air conditioner when theindoor units 10, 20, and 30 operate in cooling mode, and FIG. 4Billustrates a method for operating the air conditioner when the indoorunits 10, 20, and 30 operate in heating mode.

The method for operating the air conditioner in accordance with thepresent embodiment comprises the steps of: (S400) receiving operatingstate information of the indoor units 10, 20, and 30 connected to theoutdoor unit 40; (S500) determining whether or not the amount ofrefrigerant to be distributed into the indoor units 10, 20, and 30 needsto be regulated, based on the operating state information of the indoorunits 10, 20, and 30; and (S600) regulating the amount of therefrigerant to be distributed into the indoor units 10, 20, and 30.

Differently from the methods for operating the air conditioner inaccordance with the first and second embodiments of the presentinvention, the operating state information of the indoor units 10, 20,and 30, to be received in the step S400, includes the temperature T_(p)of each of the indoor unit conduits. Hereinafter, only a differencebetween the present embodiment and the above-described first and secondembodiments will be described for avoiding the overlapping ofdescription.

In the present embodiment, the determination step S500 comprises the substeps of: (S510) comparing the temperature T_(p) of each of the indoorunit conduits with the average temperature T_(pa) of the indoor unitconduits to calculate the operating performances of the indoor units;and (S520) determining whether or not the amount of the refrigerant tobe distributed needs to be regulated in accordance with the operatingperformances of the indoor units.

Specifically, the outdoor unit controller collects the temperaturesT_(p) of the conduits connected to all the indoor units 10, 20, and 30to thereby calculate the average temperature T_(pa). Subsequently, theoutdoor unit controller compares the average temperature T_(pa) with thetemperature T_(p) of each of the indoor unit conduits, therebycalculating the operating performance of each of the indoor units.

The outdoor unit controller classifies the indoor units into some indoorunits in which the temperature T_(p) of the associated conduit is higherthan the average temperature T_(pa) and the remainder in which thetemperature T_(p) of the associated conduit is lower than the averagetemperature T_(pa).

When the indoor units of the air conditioner operate in cooling mode asshown in FIG. 4A, the amount of the refrigerant to be distributed isregulated in the regulation step S600, so that an increased amount ofthe refrigerant is introduced into one or ones of the indoor units inwhich the temperature T_(p) of the associated conduit is higher than theaverage temperature T_(pa).

Conversely, when the indoor units of the air conditioner operate inheating mode as shown in FIG. 4B, the amount of the refrigerant to bedistributed is regulated in the regulation step S600, so that anincreased amount of the refrigerant is introduced into one or ones ofthe indoor units in which the temperature T_(p) of the associatedconduit is lower than the average temperature T_(pa).

More preferably, when it is determined that there are at least oneindoor unit in which the temperature T_(p) of the associated conduit ishigher than the average temperature T_(pa) and at least one indoor unitin which the temperature T_(p) of the associated conduit is lower thanthe average temperature T_(pa), the outdoor unit controller outputs acommand to regulate the amount of the refrigerant to be distributed.

The regulation step S600 for regulating the amount of the refrigerant tobe distributed can be carried out by regulating the sub electronicexpansion valves 11, 21, and 31 provided at the respective branchedconduits connected to the indoor units, respectively.

Of course, it can be understood that the methods for operating the airconditioner in accordance with the second and third embodiments of thepresent invention are available under the assumption that all the indoorunits have the same temperature condition as each other.

As apparent from the above description, a method for operating an airconditioner according to the present invention has effects as follows.

Firstly, according to the present invention, the amount of refrigerantto be distributed into each of indoor units can be regulated based onoperating state information of all the indoor units. This effectivelyeliminates a deviation of operating capability between the indoor unitscaused by differences in the design, manufacture, or installation of theair conditioner. As a result, it is possible to achieve not only theeffective operation of the indoor units, but also an improvement in theair conditioning efficiency of a room.

It will be apparent to those skilled in the art that variousmodifications and variations can be made in the present inventionwithout departing from the spirit or scope of the inventions. Thus, itis intended that the present invention covers the modifications andvariations of this invention provided they come within the scope of theappended claims and their equivalents.

1. A method for operating an air conditioner comprising the steps of: a)receiving operating state information of a plurality of indoor unitsconnected to one outdoor unit; b) determining whether or not the amountof refrigerant to be distributed into the indoor units needs to beregulated, based on the operating state information of the indoor units;and c) regulating the amount of the refrigerant to be distributed intothe indoor units.
 2. The method as set forth in claim 1, wherein theoperating state information includes at least one of the temperature ofair discharged from each of the indoor units, the temperature of each ofindoor unit conduits, the temperature of air suctioned into each of theindoor units, and a flow rate value of each of the indoor units.
 3. Themethod as set forth in claim 1, further comprising the step of:confirming that a controller receives the operating state informationfrom all the indoor units.
 4. The method as set forth in claim 1,wherein the step b) comprises the sub steps of: b1) calculating theoperating performance of each of the indoor units based on the operatingstate information; and b2) determining whether or not the amount of therefrigerant to be distributed needs to be regulated, in accordance withthe operating performance of each of the indoor units.
 5. The method asset forth in claim 4, wherein the operating performance is calculated bythe proportion of an actual operating capability in relation to a ratedoperating capability under a preset operation condition.
 6. The methodas set forth in claim 5, wherein the rated operating capability is apreset temperature of each of the indoor units, and the actual operatingcapability is the temperature of air discharged from each of the indoorunits under the preset operation condition.
 7. The method as set forthin claim 5, wherein the amount of the refrigerant to be distributed isregulated when it is determined that there are at least one indoor unithaving the operating performance below 1 and at least one indoor unithaving the operating performance more than
 1. 8. The method as set forthin claim 5, wherein the amount of the refrigerant to be distributed isregulated in the step c), so that an increased amount of the refrigerantis introduced into one or ones of the indoor units having the operatingperformance below
 1. 9. The method as set forth in claim 4, wherein thestep b1) comprises the step of: comparing the temperature of airdischarged from each of the indoor units with the average temperature ofair discharged from all the indoor units, to calculate the operatingperformance.
 10. The method as set forth in claim 9, wherein the amountof the refrigerant to be distributed is regulated when it is determinedthat there are at least one indoor unit in which the temperature of airdischarged therefrom is higher than the average temperature and at leastone indoor unit in which the temperature of air discharged therefrom islower than the average temperature.
 11. The method as set forth in claim9, wherein, when the indoor units operate in heating mode, the amount ofthe refrigerant to be distributed is regulated in the step c), so thatan increased amount of the refrigerant is introduced into one or ones ofthe indoor units in which the temperature of air discharged therefrom islower than the average temperature of air discharged from all the indoorunits.
 12. The method as set forth in claim 9, wherein, when the indoorunits operate in cooling mode, the amount of the refrigerant to bedistributed is regulated in the step c), so that an increased amount ofthe refrigerant is introduced into one or ones of the indoor units inwhich the temperature of air discharged therefrom is higher than theaverage temperature of air discharged from all the indoor units.
 13. Themethod as set forth in claim 4, wherein the step b1) comprises the stepof: comparing the temperature of each of indoor unit conduits with theaverage temperature of all the indoor unit conduits, to calculate theoperating performance.
 14. The method as set forth in claim 13, whereinthe amount of the refrigerant to be distributed is regulated when it isdetermined that there are at least one indoor unit in which thetemperature of the associated conduit is higher than the averagetemperature and at least one indoor unit in which the temperature of theassociated conduit is lower than the average temperature.
 15. The methodas set forth in claim 13, wherein, when the indoor units operate inheating mode, the amount of the refrigerant to be distributed isregulated in the step c), so that an increased amount of the refrigerantis introduced into one or ones of the indoor units in which thetemperature of the associated conduit is lower than the averagetemperature of all the indoor unit conduits.
 16. The method as set forthin claim 13, wherein, when the indoor units operate in cooling mode, theamount of the refrigerant to be distributed is regulated in the step c),so that an increased amount of the refrigerant is introduced into one orones of the indoor units in which the temperature of the associatedconduit is higher than the average temperature.